﻿using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text;

namespace JSharp.Java.Ast
{
    /// <summary>
    /// A line/column position.
    /// Text editor lines/columns are counted started from one.
    /// </summary>
    /// <remarks>
    /// The document provides the methods <see cref="Editor.IDocument.GetLocation"/> and
    /// <see cref="Editor.IDocument.GetOffset(TextLocation)"/> to convert between offsets and TextLocations.
    /// </remarks>
    [Serializable]
    public struct TextLocation : IComparable<TextLocation>, IEquatable<TextLocation>
    {
        /// <summary>
        /// Represents no text location (0, 0).
        /// </summary>
        public static readonly TextLocation Empty = new TextLocation(0, 0);

        /// <summary>
        /// Constant of the minimum line.
        /// </summary>
        public const int MinLine = 1;

        /// <summary>
        /// Constant of the minimum column.
        /// </summary>
        public const int MinColumn = 1;

        /// <summary>
        /// Creates a TextLocation instance.
        /// </summary>
        public TextLocation(int line, int column)
        {
            this.line = line;
            this.column = column;
        }

        int column, line;

        /// <summary>
        /// Gets the line number.
        /// </summary>
        public int Line
        {
            get { return line; }
        }

        /// <summary>
        /// Gets the column number.
        /// </summary>
        public int Column
        {
            get { return column; }
        }

        /// <summary>
        /// Gets whether the TextLocation instance is empty.
        /// </summary>
        public bool IsEmpty
        {
            get
            {
                return column < MinLine && line < MinColumn;
            }
        }

        /// <summary>
        /// Gets a string representation for debugging purposes.
        /// </summary>
        public override string ToString()
        {
            return string.Format(CultureInfo.InvariantCulture, "(Line {1}, Col {0})", this.column, this.line);
        }

        /// <summary>
        /// Gets a hash code.
        /// </summary>
        public override int GetHashCode()
        {
            return unchecked(191 * column.GetHashCode() ^ line.GetHashCode());
        }

        /// <summary>
        /// Equality test.
        /// </summary>
        public override bool Equals(object obj)
        {
            if (!(obj is TextLocation)) return false;
            return (TextLocation)obj == this;
        }

        /// <summary>
        /// Equality test.
        /// </summary>
        public bool Equals(TextLocation other)
        {
            return this == other;
        }

        /// <summary>
        /// Equality test.
        /// </summary>
        public static bool operator ==(TextLocation left, TextLocation right)
        {
            return left.column == right.column && left.line == right.line;
        }

        /// <summary>
        /// Inequality test.
        /// </summary>
        public static bool operator !=(TextLocation left, TextLocation right)
        {
            return left.column != right.column || left.line != right.line;
        }

        /// <summary>
        /// Compares two text locations.
        /// </summary>
        public static bool operator <(TextLocation left, TextLocation right)
        {
            if (left.line < right.line)
                return true;
            else if (left.line == right.line)
                return left.column < right.column;
            else
                return false;
        }

        /// <summary>
        /// Compares two text locations.
        /// </summary>
        public static bool operator >(TextLocation left, TextLocation right)
        {
            if (left.line > right.line)
                return true;
            else if (left.line == right.line)
                return left.column > right.column;
            else
                return false;
        }

        /// <summary>
        /// Compares two text locations.
        /// </summary>
        public static bool operator <=(TextLocation left, TextLocation right)
        {
            return !(left > right);
        }

        /// <summary>
        /// Compares two text locations.
        /// </summary>
        public static bool operator >=(TextLocation left, TextLocation right)
        {
            return !(left < right);
        }

        /// <summary>
        /// Compares two text locations.
        /// </summary>
        public int CompareTo(TextLocation other)
        {
            if (this == other)
                return 0;
            if (this < other)
                return -1;
            else
                return 1;
        }
    }
}
